Rock-drilling mechanism



10, 1929. E. G. GARTIN ROCK DRILLING MECHANISM Filed July 3, 1922 I gy A AJiJflAA Patented Dec. 10, 1929 UNITED STATES PATENT OFFICE ELMER G. GARTIN, F CLAREMONT, NEW HAMPSHIRE, ASSIGNOR TO SULLIVAN MA- CHINERY COFEPANY, A CORPORATION OF MASSACHUSETTS ROCK-DRILLING MECHANISM Application filed July 3, 1922. Serial No. 572,515.

My invention relates to rock drilling mech anisms and more particularly to feeding mechanisms for use in connection therewith.

An object of my invention is to provide an improved rock drilling mechanism. Another object of my invention is to provide an improved feeding mechanism for use in connection with rock drilling mechanisms. A further object of my invention is to provide an improved feeding mechanism of a type particularly adapted for use with stopers of other air fed types of drills. ther objects and advantages of my invention will hereinafter more fully appear.

In the accompanying drawings I have shown for purposes of illustration one embodiment which my invention may assume in practice.

In these drawings,-

Fig. 1 is a side elevation somewhat foreshortened of a stoping drill in connection with which the illustrative embodiment of my invention is employed.

Fig. 2 is a central vertical section through the upper end of the feeding mechanism and the lower end of the drilling motor taken upon the section line 22 of Fig. 1.

Fig. 3 is a transverse section on the line 33 of Fig. 2.

Fig. t is a fragmentary sectional View through the manual controlling valve at the motor inlet passage.

It is a well known fact that in the use of pneumatically fed rock drilling tools and particularly in the use of tools of the type known as stopers where work is being done overhead, it is possible for the operator, having cut off momentarily the air supply which has been feeding forward and maintaining the tool in contact with the rock, to run a serious risk of injury in the event that leakage of air pastthe piston and the feed mechanism causes the pressure holding the tool up to drop to a certain extent. That this is so will be clear for if the feed collapses sufficiently, the steel may retract far enough from the bottom of the holeso that upon its rear end being struck by the hammer piston it may be knocked completely out of the chuck and then, being no longer struck by the hammer, fall back out of the hole and perhaps seriously injure the miner either in falling upon his hand or arm, or upon his feet, the unsupported drilling mechanism having meanwhile moved aside being no longer supported solidly.

In the illustrative form of my invention, I have shown it employed in connection with a stoping drill which comprises a drilling motor 1 of the percussive type, a pneumatic feeding mechanism 2, and a controlling mechanism 3 which controls the supply of air under line pressure to the motor 1 through an inlet port and to the feeding mechanism 2 through a port- 2. It will herein be noted that the port 3 in the valve 3 is of such size as to permit the feed port 2 to be completely closed while maintaining the fluid supply to the drilling motor opened. A drill steel 4; is arranged to receive the percussion of the hammer piston in the motor 1. Now noting Fig. 2, it will be observed that the feed mechanism which is herein of the direct type comprises a cylinder 5 connected to a head block 6 which is disposed between the motor 1 and the feed cylinder 5. lVithin the head block is a chamber '1' with which the inlet port 3" communicates and to which air is admitted for conduction to the motor 1 so that during the entire period of operation of the motor 1 air will be contained in the chamber 7 The controlling mechanism 3 is not shown in detail as this is unnecessary for the adequate illustration of my invention, and further because it will be evident that any type of controlling mechanism which permits the supply of motive fluid to the drilling motor and the cutting off of motive fluid to the feed cylinder will be suitable for emloyment with my improved construction. l/Vithin the cylinder 5 is a feed piston 8 whose lower end is connected to a piston rod 9 terminating in a point 10 which engages an abutment of a suitable nature during drilling.

As a means of safeguarding the drill run ner from the danger which has been outlined above, I provide the improved mechanism which is generally designated 11. This comprises a valve casing 12 in which a valve 13 is reciprocable, this valve comprising spaced heads 14: and 15 separated by an annular peripheral groove 16. The valve piston 15 is provided at its lower end with an extension 17 of reduced diameter which slides in a chamber 18 forming a smaller continuation of the valve bore. The chamber 18 communicates herein by a passage 19 with the space 7 previously referred to but may obviously be connected under control of the mechanism 3 directly with a source of air pressure. The extreme upper end of the valve 13 communicates by a passage 20 with the interior of the feed cylinder 5 near the upper end thereof. A port 21 extends from the point substantially mid way of the chamber 12 to the bore of the cylinder 5.

' The valve member 13 is traversed by a longitudinal passage 26 which opens through the end of the reduced portion 17 thereof and by radial passages 27 into the groove 16. A spring 28 is arranged between a follower 29 and the lower end of the reduced extension 17 and any suitable means as the spring pressed pawl or dog 30 operates to hold the follower 29 in adjusted position.

From the foregoing description the mode of operation of my invention will be very clearly apparent. Let it be further assumed that the drill steel has bored quite a hole and that the feed piston occupies a position about half way along the cylinder 5. Now let it be assumed that in order to prevent too great pressure of the steel 4 upon the bottom of the hole, the operator momentarily cuts off a supply of air through the passage 2 to the feed cylinder and that due to'some possible distraction of his attention, he neglects to reopen this supply rather promptly. As a result of leakage the pressure above the piston 8 will fall and the weight of the drill motor, the feed cylinder, and the steel which may aggregate as much as 100 pounds in the case of a large tool will force down the motor and feed cylinder along the piston rod 9 in such manner that the drill steel 4 willbe freed to withdraw from the bottom of the hole and if, as will probably be the case, the motor 1 is still running, the piston thereof will cause the steel to reciprocate over a longer and longer path. Finally, when the drilling mechanism has collapsed to such an extent that the steel has more clearance between its upper end and the bottom of the hole than the length of the portion of the steel that enters the chuck, a blow of the piston will cause the steel to fly completely out of the chuck. This may lead to the dangerous results outlined above. WVith the provision of my improved mechanism 11, no such events can take place. As soon as the pressure within the feed cylinder has fallen to such an extent as to be just about sufficient to maintain the weight of the drill steel, the motor, and the moving parts of the feeding mechanism, the pressure which has been acting upon the larger upper area of the piston head 145 will have fallen to such an extent that the spring 28 together with the pressure which has been transmitted from the chamber 7 through the passage 19 and is acting upon the extension 17 will overbalance the reduced pressure acting upon the larger area of the piston 14 and will raise the valve 13 to such a position that communication will be established from the chamber 7 through the passage 19, port 26, radial passages 27, annular groove 16, and port 21. Accordingly the pressure within the feed cylinder and the pressure therein will rise somewhat and the parts will be held up more positively. l/Vhen the pressure in the feed cylinder rises to a sufiicient extent, the increased pressure acting upon the upper end of the spool 14 will force downward the valve and close communication between the passage 21 and the roove 16. As a result, it will be obvious that even though the drill runner were to be so forgetful as to leave the air to the feed cylinder turned off for quite some time, the mechanism would automatically operate to supply a sufficient quantity of air to the feed cylinder at proper intervals to prevent the collapse of the entire mechanism and any possible injury to the operator.

While I have in this application specifically described one form which my invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

l/Vhat I claim as new and desire to secure by Letters Patent is:

1. In a rock drilling device of the type having fluid actuated feeding mechanism and manually operable means for controlling supply of live pressure fluid to said feeding mechanism, the improvement which comprises means responsive to pressure changes in said feeding means within limits materially below line pressure for admitting live fluid directly to said feeding mechanism for maintaining the pressure therein above a predetermined minimum materially below line pressure when said manually controlled supply is closed.

2. In a rock drilling device of the type having a drilling motor, pressure fluid actuated feeding mechanism and manually operable means controlling supply of fluid to said feeding means, the improvement which comprises a valve automatically operable independently of pressure conditions in said drilling motor and in response to pressure conditions in said feeding means for admitting live pressure fluid directly to the feeding means for maintaining the pressure therein above a predetermined minimum when said manually controlled supply is closed.

3. In a rock drilling device of the type having a drilling motor, fluid actuated feeding means and a manually operable device for controlling supply of pressure fluid to said feeding means, said motor and feeding means being supplied with fluid from a common source under line pressure, the improvement which comprises a valve operable independently of pressure conditions in said drilling motor and in response to pressure changes in said feeding means and having opposed pressure areas one of which is constantly subjected to the pressure in said source and the other to pressure in said feeding means for automatically supplying fluid under line pressure from said source directly to said feeding means for maintaining the pressure therein above a predetermined minimum materially below line pressure when said manually controlled supply is closed.

4. In a rock drilling device of the type having a drilling motor, pressure fluid actuated feeding means, and manually operable means for controlling supply of fluid to the feeding means, the improvement which comprises means responsive to pressure changes in said feedin means and operated independently of pressure changes in said drilling motor for automatically opening a supplemental supply of fluid under line pressure to the feeding means after said manually controlled fluid supply is closed and whenever pressure in l feeding means drops below a predetermined minimum.

5. In a rock drilling device of the type having pressure fluid actuated feeding means, means for supplying fluid under line pressure said feeding means, and control means for said supply means, the improvement which comprises a by-pass passage for conducting a supplemental supply of pressure fluid to said feeding means, an automatic valve in said passage responsive to pressure conditions within said feeding means for automatically opening and closing said passage to regulate the supply of fluid to said feeding means in such a manner as to maintain the pressure therein from dropping below a certain predet rmined minimum materially below line pressure.

6. A rock drilling device of the type having a drilling motor, fluid actuated feeding means, a common source of fluid supply to the motor and feeding means, and a manually operable valve controlling fluid flow from said source to said motor and feeding means, the improvement which consists of means operable independently of pressure conditions in said drilling motor and responsive to pressure changes within said feeding means for automatically supplying fluid directly from said source thereto for maintaining the pressure therein above a predetermined minimum materially below line pressure when said manually controlled fluid supply to said feeding means is closed.

7. In a drilling mechanism of the type having a drilling motor, pressure fluid actuated feeding means therefor comprising relatively movable feeding elements, and controlling means for supplying fluid to said feeding means to effect relative movement between said feeding elements in one direc tion, the improvement which comprises means automatically operative to admit a separate supply of pressure fluid to said feeding means tending to prevent movement between said feeding elements in the opposite direction.

8. In a drilling mechanism of the type having a drilling motor, pressure actuated feeding means therefor including relatively reciprocable cylinder and piston elements, fluid supply means for said feeding means, and manually operable means for controlling said suppl Y to admit pressure fluid to said feeding means to eli'ect feeding movement in one direction, the improvement which comprises a supplemental fluid supply for said feed means, and means automatically operative upon reduction of pressure in the cylinder element to prevent relative movement between said feeding elements in the opposite direction by automatically opening said supplemental fluid supply.

9. In a rock drilling device of the type having a drilling mot-or adapted to actuate a drill steel, pressure fluid feeding mechanism having a feed cylinder and feed piston for feeding the motor and steel forwardly, and means for normally supplying and controlling pressure fluid to said feed cylinder, the improvement which consists of a supplemental valve responsive to pressure changes within said feeding means operable independently of pressure conditions in the drilling motor for automatically admitting live pressure fluid to the feed cylinder and main taining the pressure therein only up to a degree sufficient to hold the drill steel against the work when said normal supply to the feed cylinder is closed.

10. In a rock drill feeding mechanism of the cylinder and piston type having means for connecting a main source of pressure fluid with the cylinder and a valve for controlling the same, the improvement which consists of a supplemental source of pressure fluid for supplying said cylinder when the supply from said main source is cut off, and an automatic valve for controlling the supplemental supply having opposite ends subjected to the pressure in said cylinder and in said supplemental source respectively, said valve having a groove connected by a longitudinally extending passage with one of its ends and a port leading to the bore of said cylinder communicable with said groove.

11. In a drilling mechanism, a drilling motor, pressure fluid actuated feeding means for supporting said drilling motor and advancing the same toward the work, and means for controlling the operation of said drilling motor and of said feeding means including common supply control means for said drilling motor and said feeding means adjustable to interrupt fluid supply to said feeding means and to supply fluid to the latter to effect drilling feed, and supplemental controlling means for said fluid actuated feeding means comprising means responsive to pressure changes in said feeding means for automatically effecting, when the fluid from said feeding means supply to said feeding means is inadequate to support the drilling motor, application of suflicient force to the drilling motor to support the same in a substantially balanced condition without applying force sutficient to effect feed.

12. In a. drilling mechanism, a drill steel and drill steel actuating means, pressure fluid actuated feeding means for supporting said drill steel actuating means and advancing the same toward the work, and means for controlling the operation of said drill steel actuating means and of said feeding means including common supply control means -for said drill steel actuating means and said feeding means adjustable to interrupt fluid supply to said feeding means and to supply fluid to the latter to effect drilling feed, and supplemental controlling means for said fluid actuated,

feeding means comprising a separate valve having opposed ditlerentialareas responsive to pressure changes in said feeding means for automatically effecting, when the fluid from said first mentioned supply to said feeding means is inadequate to support thedrill steel actuating means, application of only sulficient torce to the drill steel actuating means to support the same in a substantially balanced condition without applying force sufficient to effect feed.

13. In a drilling mechanism of the type having a drilling motor, feeding mechanism therefor including relatively movable elements, a passage for normally supplying fluid to said feeding means and a manual control valve for said passage, the improvement which comprises a separate passage for conducting a supplemental supply of fluid to said feeding means when said normal supply is closed, and automatic means operative to control said last mentioned passage to control relative movein at between said feeding elements, said automatic means being operative when thepressure in said feeding mechanism drops below a predetermined minimum.

In testimony whereof I afliX my signature.

ELMER G. GARTIN.

CERTIFICATE OF CORRECTION.

Patent No. 1,739,356. Granted December 10, 1929, to

ELMER G. GARTIN.

It is hereby certified that error appears in the printed specification of the abeve numbered patent requiring correction as follows: Page 1, line 11, for the word "of" read "or"; page 2., iine 78, strike out the wards "the pressure within" and insert instead the words "fluid under line pressure will flow to"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 8th day of April, A. D. 1930.

M. J Moore, (Seal) Acting Commissioner of Patents. 

